It is well known that a coal charge in a coke oven is leveled using a leveler bar mounted on a pusher machine. The leveler bar is inserted into a chuck door opening (leveler bar opening) in the oven. While the leveler bar is inserted through the open chuck door and is reciprocating within the coke oven chamber to level the mounds of charged coal, pollutant gases can escape from the over chamber via the space between the sides of the chuck door opening and the leveler bar. Of even greater concern, air can enter the chuck door opening in a reverse direction causing vast amounts of polluting gases to escape from the charging holes at the top of the oven. Where charging cars are equipped to simultaneously charge coal into an oven, collect escaping smoke and gases and convey them into an adjacent oven, excessive in-rushing air during leveling of the charge creates a greatly increased flow of gases that may overwhelm the environmental controls on the charging car causing excess gases to escape into the atmosphere.
Early attempts at sealing the gap between the leveler bar and chuck door opening were the smoke seals disclosed in U.S. Pat. No. 2,268,316 to Taylor and U.S. Pat. No. 2,290,568 to McIntosh. These smoke seals were basically sleeves surrounding the leveler bar with a flanged front end pressed in a sealing engagement around the chuck door opening.
An improvement revealed in U.S. Pat. No. 3,821,088 to Barron provides a relatively gas-tight seal on each side of the leveler bar by urging with a yieldable mechanism two plates into a substantially perpendicular and rigid scraping contact with the side members of the leveler bar. A slidable cover plate provides a top seal while the coal withdrawn by the leveler bar into the smoke sleeve seals the bottom. While this smoke seal did afford better sealing, considerable air still passed into the over chambers. In addition, for this leveler bar seal to be effective, the leveler bar must be straight and perfectly maintained to ensure close tolerance contact with the machine fitted seal plates. Leveler bars become worn and warped through use, thus adversely affecting the sealing capabilities of these top and side seals. Of even greater concern is the fact this the smoke seal can become "frozen" in 5-7 days of continuous operation by the accumulation of tars. As the position of the leveler bar varies while reciprocating, during leveling, the side seal plates may no longer freely respond in a scraping contact with the side members of the leveler bar because of these tar deposits. Furthermore, the top seal plate, which does not readily slide on the top of the leveler bar nor ride up and down easily in the presence of a significant deposit of tars, may be sheared off if it becomes "frozen" by an excessive accumulation of tars and dirt. Extensive maintenance may thus be required.
There is thus a need for an improved gas seal between the leveler bar and chuck door opening. There is also a need for a smoke seal that operates effectively with worn and warped leveler bars as well as with those in good condition.
There is a further need for a smoke seal that will not become "frozen" and can be operated over extended periods without extensive maintenance.